STD Awareness: Antibiotic-Resistant Gonorrhea

Under the microscope, Neisseria gonorrhoeae infects larger human cells (click to enlarge). The bacteria resemble tiny pairs of coffee beans. Image: Dr. Norman Jacobs, CDC

Under the microscope, Neisseria gonorrhoeae infects larger human cells (click to enlarge). The bacteria resemble tiny pairs of coffee beans. Image: Dr. Norman Jacobs, CDC

Writing about sexually transmitted diseases (STDs), one must walk the line between warning readers of risks and engaging in full-fledged alarmism. So it’s a bit disconcerting that researchers writing in the New England Journal of Medicine last month declared that it’s “time to sound the alarm”: The emergence of completely antibiotic-resistant gonorrhea is becoming more of a realistic threat and less of a theoretical possibility. The bacteria that cause gonorrhea are evolving faster than we can develop effective antibiotics against them, and a return to the era of untreatable gonorrhea could see a rise in the particularly nasty complications that arise from a long-term gonorrheal infection, such as pelvic inflammatory disease and epididymitis.


There are genes that confer resistance to every single antibiotic we use to cure gonorrhea. If they all combine within one organism, we might have a superbug on our hands.


Neisseria gonorrhoeae is a species of tricky bacteria that cause gonorrhea, which can infect the mouth, throat, rectum, urethra, cervix, and even eyes. These bacteria have vexed us for thousands of years, having evolved many strategies for entrenching themselves in our bodies. They can alter the proteins that adorn their surfaces, rendering our immune systems incapable of recognizing them. They can form colonies in which they work together to manipulate our cell surfaces with their retracting appendages until they’re allowed entry inside, where they can surreptitiously multiply.

You’ve probably heard of MRSA, which is pronounced “mersa” and stands for methicillin-resistant Staphylococcus aureus — a strain of bacteria that has acquired resistance to methicillin, as well as pretty much every other antibiotic to boot. MRSA is an example of evolution by natural selection — what didn’t kill its ancestors made them stronger, spawning a drug-resistant strain.

Why are we talking about MRSA in a post about STDs? It’s not just because MRSA has apparently found a way to be transmitted sexually, but also because it helps make the concept of antibiotic-resistant gonorrhea more accessible. It wasn’t until less than a century ago that we finally developed a magic-bullet treatment for gonorrhea, and for a handful of decades it was quickly and easily treated with a dose of penicillin. Enter evolution by natural selection.

A bacterium (left) uses an appendage called a sex pilus to transfer copies of genes to a second bacterium. Bacteria can transfer genes that confer antibiotic resistance to one another.

Whereas mammals reproduce sexually, bacteria clone themselves asexually. But bacteria can do something else we can’t do — they can transmit genes to one another with appendages called sex pili, which can penetrate the receiving bacterium’s membrane and inject tiny pieces of DNA inside. The second bacterium is then able to express the traits coded for by the new genes. Two bacteria don’t even have to be members of the same species to give genes to one another! In this manner, copies of genes that code for antibiotic resistance can be passed around, and the recipients can reproduce themselves at a furious rate, further propagating the gene. There are many genes for antibiotic resistance out there, and if a pathogenic bacterium is lucky enough to collect ’em all, then we’ve got one mighty superbug on the loose.

We call members of Neisseria gonorrhoeae “gonococci” (singular: gonococcus), and they are unique among sexually transmitted bacteria in that they have a special talent for developing resistance to antibiotics. They can defeat antibiotics in several ways; one method involves pumping the drugs out of their cells before they can take effect. Such resistant bacteria must be inundated with ever-increasing doses of antibiotics, driving the evolution of ever-more-highly resistant bacteria. Of course, greater doses of antibiotics are accompanied by greater side effects for us humans.

Gonococci have been evolving with us for thousands of years, and the advent of antibiotics brought destruction upon many of these organisms, but also culled the herd so the strongest could survive. In the 1930s, gonorrhea was treated with sulfa drugs, to which gonococci quickly evolved resistance. In the ’40s they were slain by penicillin, but doses of this drug had to be continually increased in order to remain effective. In the ’70s, penicillin- and tetracycline-resistant gonorrhea emerged in the Pacific Basin and spread to Hawaii, California, the rest of the United States, and Europe. Fluoroquinolones were then used, but soon resistance to this antibiotic emerged as well. Since 2007, we’ve been using third-generation cephalosporins, such as ceftriaxone, considered to be our “last line of defense.” And now reports of resistance to that drug are emerging as well.

High-level ceftriaxone-resistant gonorrhea, discovered in Japan and called H041, was first isolated from a sex worker’s throat. It was found to be unusually resistant to high concentrations of ceftriaxone, as well as most of the other antibiotics tested. In lab tests, it was susceptible to spectinomycin and rifampin (unfortunately, oral gonorrhea can only be treated by an injection of ceftriaxone). Researchers confirmed that other gonococci strains were able to take up the ceftriaxone-resistance gene, showing its potential to spread in the wild population. The emergence of a gonococci strain resistant to the “last line of defense” is very bad news indeed.

There are genes out there that confer resistance to every single antibiotic we use to cure gonorrhea. So far, these genes don’t coexist side by side in one gonococcus, but because they have the ability to transfer these genes to one another, many researchers see completely antibiotic-resistant gonorrhea as an inevitability.

New antibiotics need to be designed — but this is easier said than done. Nevertheless, scientists are hard at work developing these drugs. (One Phase IV trial is currently recruiting participants with untreated gonorrhea to take an experimental combination therapy.) Additionally, there is research into a vaccine to protect against gonorrhea, although due to the shifty nature of N. gonorrhoeae’s genetic sequence this goal has eluded vaccinologists for decades.

More information about antibiotic-resistant gonorrhea is available from the Centers for Disease Control and Prevention and the National Institute of Allergy and Infectious Diseases. Sexually active people should use latex barriers, such as condoms, during vaginal, anal, and oral sex. You can be screened and treated for gonorrhea at any Planned Parenthood health center, as well as other clinics, health departments, and private health-care providers. Researchers now believe that anyone testing positive for gonorrhea should be treated and then retested three months later as a precautionary measure.

Post Script: Click here to read an update on antibiotic-resistant gonorrhea, posted to our blog in January 2013.


Click here to check out other installments of our monthly STD Awareness series!

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